This invention relates to a calculator for selectively displaying a table of data and, in particular, to a calculator having a plastic liner to facilitate movement of a slide through the calculator wherein the slide has dissimilar data on the opposite sides thereof.
In the prior art, one type of calculator includes a sliding or rotating card having a table of data printed thereon and viewable through a mask which encloses the card. Such calculators are available for a wide variety of applications, e.g. loan amortization or fill-in exposure for photographic flash. Such calculators do not actually calculate a result but display selected portions of a table or matrix of data previously calculated.
Such data is typically in the form of an independent variable displayed as rows having a particular increment or step between rows, e.g. payments in increments of twenty dollars, and a dependent variable displayed in columns, e.g. accumulated savings. The data for several variables may be displayed simultaneously in several windows, e.g. payment, interest, and number of payments.
Viewing a large table of numbers can be confusing and lead to error. In order for the tables of data to be more easily read by a user, a plurality of windows are provided in a sleeve or mask which overlies the card. For financial applications, there are many ways to present financial data for a consumer. Also, in order for the data to be useful, the incremental change between each piece of data in the table is necessarily small, requiring a large table. Thus, the same kind of data is presented on both the front side and the back side of a card.
A calculator for displaying tables of data is frequently used as a promotional item, for example by banks or other financial institutions, and is typically made from card stock which wears rapidly with use. Also, the card is often difficult to move within a sleeve. It is desired to make a calculator with a feel of higher quality and greater durability.
In view of the foregoing, it is therefore an object of the invention to provide a calculator including a sleeve and a movable slide wherein the slide is protected by a transparent, plastic lining in the sleeve.
Another object of the invention is to provide a financial calculator in which dissimilar data is printed on the reverse sides of a card, thereby enhancing the analysis of the situation modeled by the data.